1. Technical Field of the Invention
This invention relates to telecommunications networks and, more particularly, to a system and method of simulating the traffic load in a cellular radio telecommunications network.
2. Description of Related Art
In existing cellular telecommunications networks, realistic testing of new, high capacity mobile switching nodes is limited by the realism of the simulated traffic loads that are imposed on the cellular networks during the early testing phases. Generally, only a few base stations are connected, and a low level of traffic is injected into the cellular network. This makes it difficult to discover system problems which may develop under heavier traffic conditions prior to testing under real-world conditions.
Existing traffic-load simulators execute on application specific hardware, and are programmed in application specific language/scripts. Traffic is generated by executing different scripts/programs, each of which simulates a different traffic case. In order to simulate increased traffic, the existing scripts/programs must be updated, or new scripts/programs must be written to simulate additional switch hardware and mobile stations. In addition, each traffic-load simulator executes independently with no overall network coordination. Thus, there is no possibility of load sharing by means of distributing subprocesses on different target machines.
Extensive efforts have been made to resolve this situation, but existing traffic-load simulators are still not able to reproduce a load that closely resembles the real-world load experienced by MSCs in actual network operation. Therefore, the existing test environment is useful mainly for design and function testing of specific nodes, but is severely limited when it comes to multi-node testing, system testing, or mapping of customer networks. Some traffic scenarios are not currently reproducible, or are unreliable in today's environment. In addition, the existing methods of simulating cellular traffic loads all require massive amounts of hardware and maintenance, and do not provide a user-friendly interface.
Although there are no known prior art teachings of a solution to the aforementioned deficiency and shortcoming such as that disclosed herein, U.S. Pat. No. 4,680,784 to Lehnert et al. discusses subject matter that bears some relation to matters discussed herein. Lehnert discloses a traffic simulator for testing telecommunication exchanges which imitates the behavior of subscribers and lines connected to the exchange. The instantaneous behavior of the subscriber and line simulations are not predetermined, but adapt themselves randomly to system reactions. The traffic simulator includes a circuit for producing the subscriber and line simulations, a circuit for determining event instants, a circuit for producing random event variables, an interface for transmitting absolute simulation instants to the exchange, and a simulation control to which the exchange transfers reports of received events. The reaction times of the exchange can then be measured without measuring the internal time delays of the simulator.
Lehnert, however, has several disadvantages. First, the Lehnert simulator is designed for wireline telecommunication switches, and therefore, does not account for many conditions encountered in cellular systems which change the traffic load parameters and affect switch performance. For example, Lehnert does not address radio propagation conditions, signal strength from mobile stations, bit error rates on uplink and downlink channels, etc. Cellular switches have to measure all these conditions for each mobile station and determine when to hand off the mobile station from its serving cell to a neighboring cell in which the radio conditions are better. Additionally, the Lehnert simulator is hardware dependent, and is programmed in application specific scripts. Thus, to simulate increased traffic, the existing scripts must be updated, or new scripts must be written. Finally, the Lehnert simulator simulates subscriber behavior such as lifting the receiver, flashing the hook switch, dialing certain numbers, etc. It does not simulate differing mobile station capabilities and/or radio conditions. Therefore, Lehnert reveals no disclosure or suggestion of a cellular network traffic simulator such as that described and claimed herein.
In order to overcome the disadvantage of existing solutions, it would be advantageous to have a cellular network traffic simulator that is not hardware dependent, and accounts for standardized call routines conducted over the air interface, differing mobile station capabilities, differing radio conditions, and differing call scenarios as mobile stations roam throughout the service area of the cellular network. Such a simulator would be able to simulate a realistic traffic load that closely resembles the real-world traffic load experienced within a cellular network. Utilizing the simulator during the early testing phases of MSCs would result in more robust systems that would be significantly less likely to fail when experiencing real-world traffic conditions. The present invention provides such a traffic simulator.